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Perturbation of longitudinal relaxation rate in rotating frame (PLRF) analysis for quantification of chemical exchange saturation transfer signal in a transient state
Author(s) -
Wang Yi,
Zhang Yaoyu,
Zhao Xuna,
Wu Bing,
Gao JiaHong
Publication year - 2017
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.26559
Subject(s) - saturation (graph theory) , chemistry , nuclear magnetic resonance , perturbation (astronomy) , amplitude , imaging phantom , relaxation (psychology) , analytical chemistry (journal) , physics , mathematics , optics , chromatography , psychology , social psychology , quantum mechanics , combinatorics
Purpose To develop a novel analytical method for quantification of chemical exchange saturation transfer (CEST) in the transient state. The proposed method aims to reduce the effects of non‐chemical‐exchange (non‐CE) parameters on the CEST signal, emphasizing the effect of chemical exchange. Methods The difference in the longitudinal relaxation rate in the rotating frame ( Δ R 1 ρ) was calculated based on perturbation of the Z‐value byR 1 ρ, and a saturation‐pulse‐amplitude‐compensated exchange‐dependent relaxation rate (SPACER) was determined with a high‐exchange‐rate approximation. In both phantom and human subject experiments, MT R asym(representative of the traditional CEST index), Δ R 1 ρ, and SPACER were measured, evaluated, and compared by altering the non‐CE parameters in a transient‐state continuous‐wave CEST sequence. Results In line with the theoretical expectation, our experimental data demonstrate that the effects of the non‐CE parameters can be more effectively reduced using the proposed indices ( Δ R 1 ρand SPACER) than using the traditional CEST index (MTR asym). Conclusion The proposed method allows for the chemical exchange weight to be better emphasized in the transient‐state CEST signal, which is beneficial, in practice, for quantifying the CEST signal. Magn Reson Med 78:1711–1723, 2017. © 2016 International Society for Magnetic Resonance in Medicine.